The present disclosure relates to an apparatus and a method for generating sinusoidal waves, and a system for driving a piezoelectric actuator using the same.
As interest in user interfaces is on the rise and related technologies advance, it is essential for user interfaces to be provided with technology for providing responses to user input in various terminals.
At the early stages thereof, response technology was provided to allow users to intuitively confirm that user input had been received by simply providing vibrations.
Recently, it has become essential to provide precise responses or vibrations in response to user input, and accordingly, providing vibrations with greater precise has become an important issue. Therefore, touch response technology has advanced from conventional motor-driven technology to haptic technology, able to provide various types of response to users.
Haptic technology refers to an overall system for providing tactile feedback to users, and such feedback may be provided to users by vibrating a vibration element to deliver physical impulses. In the early stages thereof, the haptic technology merely provided simple confirmation of user input. Recently, however, haptic technology has been required to provide various types of response to emotional feedback, based greater precision in the controlling thereof.
To this end, it is required to provide three-dimensional vibration patterns using various frequency bands, and in order to meet this requirement, a piezoelectric actuator formed of ceramic material has recently been employed. Such piezoelectric actuators have advantages over existing linear resonant actuators or vibration motors with magnets in that they have faster response speeds, generate less noise, and have higher resonant bandwidths. Accordingly, minute and three-dimensional vibrations can be variously realized.
Since such a piezoelectric actuator uses sinusoidal waves for its driving signal, it is essential for more precise control to generate sinusoidal waves more precisely with no distortion. In other words, because the piezoelectric element is driven with sinusoidal waves, it is necessary to obtain wave accuracy of sinusoidal waves generated from a piezo driving device in order to accurately drive the piezoelectric element.
According to the technology for driving a piezoelectric actuator in the related art, in order to precisely generate sinusoidal waves, a look-up table having high-resolution digital values stored therein and a high-resolution digital-to-analog converter are used. Since the digital values stored in the look-up table are determined based on a base frequency and a sampling frequency, when a target frequency a user desires is greatly increased, the peak value of sinusoidal waves deviates from the target value.